Engine Block (Supplementary Information)

Engine block




1. Cylinder sleeves
2. Piston
3. Gudgeon pin
4. Sodium cooled exhaust valve
5. Camshafts
6. Intake port
7. Piston cooling nozzle
8. Piston cooling cover
The engine block has been modified in the following areas compared to the B5254S :
- Cylinder diameter is reduced (from 83 to 81 mm) to increase the cylinder sleeve thickness (1).
- The reinforced pistons (2) have a smaller diameter and a more concave crown to reduce the compression ratio. The bottom of the pistons have a cut out for the piston cooling nozzles.
- The gudgeon pins (3) are reinforced, with for example a smaller center hole.
- Exhaust valves (4) are sodium cooled, because if the high temperatures.
- Camshafts (5) have lower lift. This gives better idling quality and comfort without reducing the power.
- Intake ports (6) are also modified because of the absence of the variable intake manifold.
- Outlets in the cylinder block for the piston cooling nozzles (7) and relief valves. These have three covers (8) on the outside of the block.
The special spark plugs can tolerate very high temperature and pressure and retain the old service interval.
The crankshaft and thrust bearing have been modified to meet the higher loads on the crank mechanism in the turbo engine which also affect other 5 and 6 cylinder engines:
- The grooves in the lower bearing are eliminated, raising the oil pressure and providing a better oil film.
- The material quality in the big end bearing has been improved, the lead-bronze alloy has been replaced by a more heat resistant aluminum alloy.